1. Field of the Invention
The present invention relates to a semiconductor device for use in, for example, a power converter to be mounted on a mobile object such as an automobile and, more particularly, relates to a structure and a mounting method of a power semiconductor module for use in an inverter or the like.
2. Description of the Related Art
FIG. 3 is a typical view of cross sectional structure of a general power semiconductor module which is for use in, for example, a power converter. In FIG. 3, a semiconductor switching element (hereinafter, referred to as merely “semiconductor element”) 1 such as an insulated gate bipolar transistor (IGBT) and a free wheel diode 2 are bonded by soldering to an upper circuit 3 on an insulating member 5; and a lower circuit 4 on the insulating member 5 is bonded to a metal base 13 formed with fins 12 via a bonding layer 10 of solder or sintering material.
A cover 14 is fixed to the metal base 13 and thus cooling water passages are formed; and the fins 12 are directly cooled and thus a reduction in thermal resistance from the semiconductor element 1 and the free wheel diode 2 to cooling water is achieved.
Furthermore, in Patent Document 1, a lower circuit of an insulating substrate is omitted and an insulating substrate is bonded to a low stiffened and soft metal base with fins and thus a reduction in thermal resistance and high reliability are achieved.